ST segment elevation myocardial infarction (STEMI) is associated with high mortality despite advancements in medical technologies and more frequent primary percutaneous intervention (PPCI) procedures. Vasoconstriction and the presence of thrombus burden during STEMI can lead to stent under-sizing and subsequent late mal-apposition. The DynamX Sirolimus-Eluting Coronary Bioadaptor System has been developed with unique mechanism of unlocking the bioadaptor frame at 6 months and hence uncaging the vessel, helping to restore vessel function and allow positive adaptive re-modelling. Its application in STEMI patients might therefore help to avoid late acquired mal-apposition. Despite some clinical studies had demonstrated safety use of DynamX in de novo coronary artery disease, its application in STEMI patients had not been well studied. We aim to assess the safety and effectiveness of STEMI patients treated with the bioadaptors during PPCI in our institute.

This is a single-centered retrospective study. Medical records of 42 STEMI patients with de novo coronary artery disease implanted with DynamX bioadaptor in PPCI procedures between from April 2022 and October 2023 at the United Christian Hospital in Hong Kong were retrieved and analyzed. Patients who received thrombolytic were excluded from the study. Patients were followed up for 12 months. The study end-points included Major Adverse Cardiac Event (MACE) rate, which is a composite of all-cause mortality, cardiovascular death and myocardial infarction, ischaemia-driven target lesion revascularization (TLR) and procedural success rate. 

Medical records of 42 STEMI patients implanted with DynamX bioadaptor in PPCI procedures were analyzed. Mean age was 58 years ± 10 years. The mean Global Registry of Acute Coronary Syndrome (GRACE) risk score was 117 ± 34. 100% procedural success rate was achieved. 2 MACE events occurred with 2 deaths happened before discharge. One of the patient presented with out-of-hospital cardiac arrest and cardiogenic shock requiring upfront Impella support. The other patient suffered from pulseless ventricular tachycardia 1 day after index procedure. No acute myocardial infarction and ischaemia-driven target lesion revascularization were observed throughout 12 months. Among 42 patients, 8 patients undergone follow-up coronary angiogram with a mean follow-up days of 213 from index procedure. Late luminal gain was observed on follow-up coronary angiogram. The mean in-device late lumen loss of -0.21 ± 0.15mm and mean change in diameter stenosis -0.64 ± 4.20%.
Baseline characteristics of patients with STEMI treated with PPCI

Baseline Characteristics	Total(n=42)
Age, mean ± SD (years)	58 ± 10
Gender: Male	39 (93%)
Current Smoker	27 (64%)
Diabetes mellitus	11 (26%)
Hypertension	14 (33%)
Dyslipidemia	13 (31%)
Chronic Kidney Disease	5 (12%)
Previous percutaneous coronary intervention (PCI)	0 (0%)
Previous coronary artery bypass graft (CABG)	0 (0%)
GRACE Score, mean ± SD	117± 34

 Peri-procedural characteristics of patients with STEMI treated with PPCI

Peri-procedural Characteristics	Total(n=42)
Culprit Vessel
Left Main	1 (2.4%)
Left anterior descending	30 (71.4%)
Left circumflex	3 (7.2%)
Right coronary	8 (19.0%)
Single vessel disease	26 (61.9%)
Average stent length	35 mm
Average stent diameter	3.3 mm
Stent overlap	3
Bifurcation
Provisional	21 (50%)
Jailed Balloon Technique	13 (32.5%)
Culotte	2 (4.76%)
Lesion Type
A	6 (14%)
B1/B2	28 (67%)
C	8 (19%)
Radial Access	33 (78.6%)
Thrombectomy	17 (40.5%)
Procedural success	42 (100%)

This single centered retrospective study shows that the use of DynamX bioadaptor in STEMI patients for PPCI procedures is safe and feasible with favorable 12-months clinical outcome and evidence of positive adaptive remodelling and late luminal again.